Trimming mechanism



IAug. 27, 1957 s, G, BRADY TRIMMING MECHANISM 5 Sheets-Sheet 1.

Filed Oct. 5, 1955 ATTO RN EYS Aug- 27, 1957 s. G. BRADY 2,804,064

TRIMMING MECHANISM Filed Oct. 3. 1955 5 Sheets-Sheet 2 N /f Ba L/ il l 1/ AWA HG2. A..

INVENTOR.

SAMUEL @BRADY I ATTORNEYS Aug. 27, 1957 s. G. BRADY 2,804,064

TRIMMING MECHANISM Filed 001'.. 3, 1955 5 Sheets-Sheei 3 O H65. QIA j; F|G.4.

TSJ lie l' M w M P M Q r-r- A FIGS., LAQ FIG?.

INVENTOR. sAMul-:x s. BRADY WL #www ATTORNEYS United States Patent TRIMMING MECHANISM Samuel G. Brady, Birmingham,

Gear Grinding Machine Company, corporation of Delaware Mich., assigner to The Detroit, Mich., a

The invention relates to trimming mechanisms for form grinding machines and more particularly to machines for grinding gears. It is the usual practice to employ a pantograph for actuating the diamond trimming cutter and to control the movement of the pantograph by a template or pattern. For grindingy gear teeth the trimmer may include two of these pantograph mechanisms for respectively fashioning the grinder wheel with involute contours corresponding to opposite sides of the gear tooth. Usually the grinder wheel is trimmed to a cross sectional contour corresponding to the interdental space of the gear wheel so that in the grinding operations the adjacent involute contours of the adjacent gear teeth are simultaneously ground. These trimmed contours do not, however, extend across the interdental space for which, if ground, an additional trimmer is required.

In the manufacture of gears it has been found that the fashioning of the root portion of the gear tooth in its relation to the interdental portion thereof, is of great irnportance and contributes largely to the strength of the structure. Thus the tooth will be strengthened by the forming of a llet at the base of the involute portion which merges into the surface between the teeth.

It is one of the objects ofthe invention to obtain a trimming mechanism of the type above referred to in which each pantograph controlled trimmer is adapted to trim not only the involute contour but also to extend the same around the root portion of the tooth and the line between the same and the adjacent tooth. It is a further object to avoid any interference between the two cutters in this extended movement thereof. Another object of the invention is to provide a detachable diamond cutter unit for each pantograph in which unit the diamond is positioned so that when mounted on the pantograph it will be correctly positioned in relation thereto. This avoids the necessity of adjusting the diamond while mounted on the pantograph to compensate for wear and permits of at any time substituting an exchangeable unit in which the diamond is properly positioned, thereby avoiding loss of time in the operation of the grinder. With these objects in View the invention consists in the construction and arrangement of the patterns controlling the respective pantographs and the mechanism for actuating each pantograph follower along the extended contour of its pattern.

In the accompanying drawings:

Fig. l is a front elevation of the trimming mechanism assembly.

Fig. 2 is a section on line 2-2 Fig. l.

Fig. 3 is an elevation of the exchangeable trimming unit.

Fig. 4 is a section on line 4-4 Fig. 3.

Fig. 5 is a section on line 5-5 Fig. 4.

Fig. 6 is a section on line 6-6 Fig. 4.

Fig. 7 is an end elevation looking upward Fig. 4.

Each of the trimming mechanisms includes two separate pantographs mounted on a suitable frame which,

2,804,064 Patented Aug. 27, 1957 ice 2 as shown, is a box-like structure A. Both pantographs B and C are located between front and rear walls A and A2 of this frame and are mounted upon stationary pivot pins D and E extending between said walls parallel to each other. Each pantograph is a parallelogram frame including the main lever members B and C which are directly mounted respectively on the pins D :and E, which form the fulcrums therefor. These members also constitute long sides of the parallelogram frame and the ratio in length of the arms on opposite sides of the fulcrum determine the reduction in size between the controlling patterns and the trimmed contours. The other members of the parallelogram include sides B2 and C2 of equal length to the levers B and C', and short sides B3B4C3C4 all being pivotally attached to each other. The sides B3C3 have mounted thereon the trimming cutters and the sides BC1 have the followers for tracing the patterns.

The base of the frame A is of greater width than the upper portion thereof and has at opposite sides of the rear wall A2 embossments A3 and A4 for the mounting of pattern members F and G (shown in dotted lines, Fig. l). These are contoured to include involute portions F' and G corresponding to the sides of adjacent gear teeth on opposite sides of the interdental spaces and top portions F2 and G2 corresponding to the root portions F2, G2 of these teeth. The root contours are extended across the interdental space so that the trimming cutters actuated thereby would interfere with` each other if simultaneously operated. This difficulty I have avoided by providing mechanism for operating the pantographs by which the followers tracing the patterns are out of phase with each other so that there will be no interference between the cutters controlled thereby.

The operating mechanism includes a pair of piston and cylinder fluid actuated motors H and I arranged in the lower portion of the frame, the cylinders being respectively pivotally anchored at opposite sides of the base thereof as indicated at H and I. The pistons H212 have their rods H313 pivotally connected respectively with the pantograph members C4 and B4. These members also have extensions B5C5 on which are mounted follower rollers BSC6 for tracing the contours of their respective patterns F and G. The arrangement is such that outward movement of each piston will advance its corresponding follower roll upward along the involute contour of the pattern and will continue the movement over the top portion thereof. The reverse movement of the piston will move the follower in the opposite direction. However, to retain the follower in contact with the pattern contour, coil springs l andl are anchored at opposite sides of the base and are connected respectively to the members B4 and C4.

The hydraulic fluid for actuating the pistons and the cylinders is controlled by a valve K having a pressure uid inlet K' and a return K2 to the storage tank (not shown). The valve is also connected by a conduit K3 to the anchor end of the cylinder H, and by another conduit K4 to the anchor end of the cylinder I. A flexible conduit K6 connects the outer ends of the cylinders H and I to each other for passage of fluid therebetween. A solenoid K5 is used for actuating the valve and in one position connects the inlet K with the conduit K3 and the conduit K4 to the outlet K2. In another position of the valve the inlet K' is connected to the conduit K1 and the conduit K3 to the outlet K2. Thus in operation the pistons will be normally at opposite ends of their respective cylinders and when actuated by hydraulic fluid one piston will be moved outward in its cylinder while the other piston is moved inward. This will insure that the trimming mechanisms actuated thereby will not interfere with each other.

To avoid delays in the grinding operations I have provided exchangeable diamond cutter units which, when attached to the pantograph will correctly position the cutter in reference thereto. Each of these' exchangeable units comprises a block L having a channel L of V- shaped cross section extending longitudinally thereof and adapted to receive a polygonal bar member M at one end of which a diamond N is set. A cap O closes the channel L being secured to the block L by screws O and set screws O2 extending through this cap bear against the outer face of the bar M and press it into contact with the V faces of said channel. The cap O has at one end an L-shaped portion O3 overlapping thechannel and a set screw 1 in the portion O3 bears against the end of the bar M opposite that on which the diamond is mounted to adjust said bar longitudinally. The block L is attached to the outer face of a head P which in turn is non-rotatively secured to the outer end of a shaft Q which, at its inner end, forms one of the pivots of the pantograph and is non-rotatively attached to the member 1?3 or C3 thereof. To accurately position the block L with respect to the head P an end portion Q of the shaft Q projects beyond said head and engages edge faces L2L3 of the block L which are at right angles to each other. A cap L4 secured to the block L embraces the opposite side of the projecting portion of the shaft Q and a set screw L5 in said cap contacts with the shaft to draw the surfaces L2 and L3 into contact therewith. The block L is further secured and positioned with respect to the head P by a member R secured by screws R to the other end of said block and having a projecting portion R2 which extends into a recess P in the end of the head P. One face of the projection R2 is pressed against a face P2 of the recess P by a set screw P3 in the portion on the opposite side of said recess. This exactly positions the angle of the block L with respect to the head P about the axis of the pivot and it is secured to said head by a pair of screws S.

With the construction of the unit as just described the diamond may be positioned with reference to the block L when the latter is detached from the pantograph mechanism. Thus when it is mounted on the pantograph it will be exactly positioned with reference thereto. When wear in the diamond occurs, a unit may be detached and replaced by another unit.

What I claim as my invention is:

l. In a trimming mechanism for gear grinding machines of the type comprising a frame, separate pantograph actuated trimming cutters for fashioning opposite sides of a grinder wheel to a contour corresponding to the contours of gear teeth on opposite sides of an interdental space; a pattern for each pantograph mounted on said frame and which is extended to include a root portion of the tooth merging into an interdental contour having portions in common in the two patterns corresponding to the same portion of contour to be traced by each cutter, a follower on each pantograph for engaging its pattern, and means for actuating each pantograph to sil1r 1 ulta 13 plously trace by its follower the full pattern contour including said extended portion but with their respective movements out of phase to avoid interference between said cutters.

2. The construction as in'claim l in which said extended portion of each pattern includes at least one half of the interdental contour.

3. The construction as in claim 1 in which said actuating means includes for each pantograph a piston and cylinder hydraulic motor link pivotally connected at opposite ends respectively to an anchor point on said frame and to said pantograph, said link extending at an angle to its pattern so as to travel the entire length of the contour by relative movement of the piston and cylinder.

4. The construction as in claim 3 including resilient means for biasing each follower to maintain contact with the pattern contour during travelling movement thereover. v

5. In a trimming 'mechanism for form grinding machines of the type including a pantograph for actuating the trimmer cutter, and a pattern for guiding said pantograph; an exchangeable cutter unit and a mounting therefor on the pantograph comprising a block having a channel therein and a rod longitudinally adjustably secured in said channel having the cutter xed to the outer end thereof, said block having at one end thereof adjacent edge faces at an angle to each other and at one side of the outer end portion of said channel also having a portion spaced from said angle faces projecting downward beyond the bottom face of said block, a head on said pantograph constituting the trimming arm thereof and having a face parallel to the plane of movement on which said block is mounted, means for exactly positioning said block on said head, including a cylindrical projection from said face of said head which is coaxial with the pivot connecting said arm with another side member of the pantograph, said projection forming a stop for said adjacent edge faces, a stop on said head for said downward projecting portion tion of said block relative to said head about the axis of said pivot, and clamping means for securing said block to said head in contact with said stops.

6. The construction as in claim 5 in which the channel in said block has faces at an angle to each other and said bar has cooperating contacting faces for holding the same from rotation, a cap for clamping said bar in said channel, an angle flange on said cap extending over the rear end of said channel and a screw threadedly engaging said flange for adjusting said bar longitudinally in said channel before clamping.

References Cited in the le of this patent UNITED STATES PATENTS 2,274,543 Gruenberg V Feb. 24, 1942 2,274,561 Pernack Feb. 24, 1942 2,335,341 Knowles s Nov. 30, 1943 2,358,393 Greve Sept. 19, 1944 determining the angular posig.v 

